Yamaha 90hp 4-stroke fuel coming out of the carbs

[wjwyatt]

I'll start out by saying that I'm not a mechanic. I've never worked on a boat engine so if I say something ridiculous, please laugh with me

I have a 90 hp Yamaha outboard (2003 model I believe) on a small 17' dura-craft. It's been sitting up for a long time. Probably hasn't been cranked in 8-9 months. We were going to take it out tomorrow so I went to get it ready. Tried to crank it and it seemed to crank right away after choking. However, after removing the cowling I noticed fuel coming out of the carburetors (see attached picture). I shut the engine down. I noticed that when I pump the fuel ball, fuel squirts out of 2 holes near the arrows shown in the picture (not all 4........this was just a picture I found on the web). Anyhow, we put 'er up until I can figure out what's going on. Any input would sure help! I've searched for "float stuck", "diaphragm leak", etc......no idea what I'm doing

Thanks guys
- Jeremy

 

[Yamajoe]

Re: Yamaha 90hp 4-stroke fuel coming out of the carbs

The float needle valve/s are stuck open or badly worn causing fuel to exit from the overflow ports, you need to overhaul your carbs.

 

[ruffinit]

Re: Yamaha 90hp 4-stroke fuel coming out of the carbs

I, too, will need to have the carbs cleaned on my 2003 50hp. I have the service manual, but am not too confident I can get this right. Is it worth letting the dealer do it to make sure it gets done right? How much should this cost at a dealer?

 

[Yamajoe]

Re: Yamaha 90hp 4-stroke fuel coming out of the carbs

You need a good manual, some basic tools, a reasonable tach, a vacuum tester or manometer (this is essential), and voltmeter, carb cleaner, clean workbench and patience.

I find working on these carbs so much less time consuming (less fiddley) than my 2 stroke 60hp. The vacuum test tool is used to synchronize the carbs.

 

[rodbolt]

Re: Yamaha 90hp 4-stroke fuel coming out of the carbs

I have to agree with Yamahajoe,except I think I misread the 4 stroke carb VS 2 stroke carb part .
the four stroke carbs are usually much more finnicky,not to mention way more aggrevating to remove and install.
usually take me about 4 hours to do the carbs on the F90 and F50 depending on the severitry of the varnish buildup.
normally kits are not needed but if they are they are in the 80 dollar per carb range,but all orings and needles are availble seperatly.
the passages are very very small,usually for the pilot fuel jet you have to run a small strand of copper wire through it to adequatly remove the varnish buildup.
these carbs are very very intolerant to any debris/varnish buildup.
and on the F90 there is no "choke" its a prime start setup that automatically enrichs the air fuel mix for starting at various air/engime temps.
pushing the choke switch does absolutly nothing and raing the warm up lever to advance the throttle can make starting impossible.
this system,when working properly,requires no other action from the operator other than filling the fuel bowls with fuel with the primer and turning the key to start.
the F/T 50 motors from 01 and up are the same way.
as far as cost,depends on the damage.
the 03 F50 carb kits are about 87 dollars apiece ,I did a set last june that the ethanol fuel we got had dissolved the tank draw tube and fuel sender float.
took me 8 hours to clear the fuel systm,carbs and intake and valve train of the sticky residue left in the system.
did an F90 thursday that took me 3 hours to remove,dissasemble/clean and reinstall the carbs.
the F90 is mounted on a 72 Boston Whaler.
we were getting E-10 crap but it was NOT posted.
the customer added 18 gallons of E-10 crap to his factory fiberglass Whaler tank.
a week later I got to clear the fiberglass resin from the engine and fuel systems.

 

[wjwyatt]

Re: Yamaha 90hp 4-stroke fuel coming out of the carbs

Well, I had a friend tell me yesterday that I could basically just let the engine run for a few minutes and the fuel would stop leaking out after the float un-sticks Apparently there's a little cup-looking thing below the carbs that catches this fuel....almost as if Yamaha expected this to happen at some point Can I do this (just let it run) and put some carb cleaner in the fuel to fix the problem? The engine is brand new......just been sittin' for a while.

 

[rodboltw]

Re: Yamaha 90hp 4-stroke fuel coming out of the carbs

you can try it.
worst your gonna do is tear out the rings on that cylinder or set the engine on fire.

 

[wjwyatt]

Re: Yamaha 90hp 4-stroke fuel coming out of the carbs

Well, I tried. The engine wouldn't even crank this go around. Any suggestions on where to take it for repair in the Pensacola area anyone?